syzbot


INFO: task hung in vfs_link

Status: upstream: reported on 2025/04/22 03:53
Reported-by: syzbot+d499ea9c6716b7c5bf1f@syzkaller.appspotmail.com
First crash: 71d, last: 71d
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in vfs_link bcachefs 5 177d 206d 0/29 auto-obsoleted due to no activity on 2025/04/05 19:52

Sample crash report:
INFO: task syz.0.1371:10983 blocked for more than 144 seconds.
      Not tainted 5.15.180-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1371      state:D stack:26912 pid:10983 ppid:  4166 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 rwsem_down_write_slowpath+0xf0c/0x16a0 kernel/locking/rwsem.c:1165
 inode_lock include/linux/fs.h:787 [inline]
 vfs_link+0x53f/0x810 fs/namei.c:4548
 do_linkat+0x5c8/0x9d0 fs/namei.c:4628
 __do_sys_link fs/namei.c:4662 [inline]
 __se_sys_link fs/namei.c:4660 [inline]
 __x64_sys_link+0x82/0x90 fs/namei.c:4660
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1ee22bf169
RSP: 002b:00007f1ee00e5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007f1ee24e7160 RCX: 00007f1ee22bf169
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000200000000200
RBP: 00007f1ee2341a68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f1ee24e7160 R15: 00007ffe6ecd7e18
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8cb1f4e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/1:2/1108:
 #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90004d47d20 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
2 locks held by getty/3928:
 #0: ffff88802c97e098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900025c62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1db0 drivers/tty/n_tty.c:2158
2 locks held by kworker/0:6/4214:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc9000316fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
1 lock held by udevd/4736:
4 locks held by kworker/u4:9/5110:
 #0: ffff8881429b0938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc900032bfd20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff8880216020e0 (&type->s_umount_key#80){++++}-{3:3}, at: trylock_super+0x1b/0xf0 fs/super.c:418
 #3: ffff88807cefd1b0 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x4d4/0x6a0 fs/f2fs/segment.c:528
2 locks held by kworker/u4:10/5129:
 #0: ffff8880b8f3a318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
 #1: ffff8880b8f27848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x53d/0x810 kernel/sched/psi.c:891
3 locks held by kworker/1:15/5495:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc9000365fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #2: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x280/0x740 kernel/rcu/tree_exp.h:845
1 lock held by syz-executor/8567:
 #0: ffff8880793e20e0 (&type->s_umount_key#55){++++}-{3:3}, at: deactivate_super+0xa9/0xe0 fs/super.c:365
6 locks held by syz.0.1371/10980:
3 locks held by syz.0.1371/10983:
 #0: ffff888021602460 (sb_writers#24){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:377
 #1: ffff888074fbd6d0 (&type->i_mutex_dir_key#18/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
 #1: ffff888074fbd6d0 (&type->i_mutex_dir_key#18/1){+.+.}-{3:3}, at: filename_create+0x25c/0x530 fs/namei.c:3835
 #2: ffff888074fbe050 (&sb->s_type->i_mutex_key#28){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #2: ffff888074fbe050 (&sb->s_type->i_mutex_key#28){+.+.}-{3:3}, at: vfs_link+0x53f/0x810 fs/namei.c:4548
1 lock held by syz-executor/11127:
 #0: ffff888066dfa0e0 (&type->s_umount_key#55){++++}-{3:3}, at: deactivate_super+0xa9/0xe0 fs/super.c:365
2 locks held by syz.2.1488/11595:
 #0: ffff8880216020e0 (&type->s_umount_key#80){++++}-{3:3}, at: iterate_supers+0xac/0x1e0 fs/super.c:716
 #1: ffff8880216467d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff8880216467d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x274/0xab0 fs/fs-writeback.c:2768
1 lock held by syz-executor/11745:
 #0: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #0: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x350/0x740 kernel/rcu/tree_exp.h:845
3 locks held by kworker/0:22/11968:
 #0: ffff8881427d7938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90004e27d20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffff888024be7220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline]
 #2: ffff888024be7220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe72/0xeb0 kernel/hung_task.c:369
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 12134 Comm: kworker/u4:12 Not tainted 5.15.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: bat_events batadv_mcast_mla_update
RIP: 0010:unwind_next_frame+0x12bc/0x1fa0 arch/x86/kernel/unwind_orc.c:592
Code: 84 c0 0f 85 41 0b 00 00 49 0f bf 04 24 48 01 c5 4c 89 ff 48 89 ee 48 89 da eb 3f 49 8d 5e 02 49 83 c6 03 48 89 d8 48 c1 e8 03 <0f> b6 04 10 84 c0 0f 85 33 0b 00 00 4c 89 f0 48 c1 e8 03 0f b6 04
RSP: 0018:ffffc90003727548 EFLAGS: 00000a06
RAX: 1ffffffff1d01128 RBX: ffffffff8e808940 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffffc900037276c0
RBP: ffffffff8e808942 R08: ffffc90003727700 R09: ffffc900037276b0
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffffffff1d01128
R13: 1ffffffff1d01128 R14: ffffffff8e808941 R15: ffffc90003727660
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d13cd57ff8 CR3: 0000000073f0d000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __unwind_start+0x59d/0x720 arch/x86/kernel/unwind_orc.c:704
 unwind_start arch/x86/include/asm/unwind.h:60 [inline]
 arch_stack_walk+0xdb/0x140 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x113/0x1c0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc+0xba/0xf0 mm/kasan/common.c:513
 kasan_kmalloc include/linux/kasan.h:264 [inline]
 kmem_cache_alloc_trace+0x143/0x290 mm/slub.c:3247
 kmalloc include/linux/slab.h:604 [inline]
 batadv_mcast_mla_softif_get_ipv4 net/batman-adv/multicast.c:373 [inline]
 batadv_mcast_mla_softif_get net/batman-adv/multicast.c:500 [inline]
 __batadv_mcast_mla_update net/batman-adv/multicast.c:878 [inline]
 batadv_mcast_mla_update+0xb5e/0x3b90 net/batman-adv/multicast.c:915
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/22 03:52 linux-5.15.y f7347f400572 2a20f901 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in vfs_link
* Struck through repros no longer work on HEAD.